Method of promoting the adherence of cellulose ester emulsions onto film bases



Dec. 21, 1943. w. 'PARTRIDGE. JR 2,337,345

METHOD OF PROMOTING THE ADHERENCE OF CELLULOSE ESTER EMULSIONS ONTO FILMBASES Filed March 5, 1942 Fllll.

SILVER HALIDE-CELLULOSE ESTER EMULSION (APPARENT ACETYL 21.5%) CELLULOSEZSZAP OF3I.9% APPARENT ACETYL ESTER SUB{ 75,LAP 0F 29.61- n CELLULOSE{zszAP OF 29.6% APBARENT ACETYL ESTER SUB 757. AP CF 32.6% I

CELLULOSE EsrER SUPPORT (401, APPARENT ACETYL)- FIE-1.2.

SILVER HALlDE-CELLULOSE ESTER EMULSION (APPARENT ACETYL 2:57

CELLULOSE 701 AP OF 3|.9Z APPARENT ACETYL ESTER SUB 307 AP CF 28.2%

CELLULDSE 491 AP 0F 35.7% APPARENT ACEJTYL ESTER sue 517. AP OF 29.974

cELLuLosE ESTER SUPPORT(40'Z APPARENT ACETYL) W! NFIELD PARTRIDBEHJRJINVENTOR ATT EYS Patented Dec. 21, 1943 METHOD OF PROMOTING THEADHERENCE OF CELLULOSE. ESTER. EMULSIONS ONTO FILM BASES WinfieldPartridge, Jr., Rochester, Y., assignor to Eastman Kodak Company,Rochester, N. Y.,

a corporation of New Jersey Application March 5,1942, Serial No. name 11Claims. .(Cl. 95-9) use as the carrier for the silver halide. Not onlyThis applicatipn relates to the subbing of photographic film havingthereon cellulose ester "photographic emulsions to cause the adherenceof those emulsions to the cellulose ester film base.

Recently the use of far-hydrolyzed cellulose esters, as carriers for thesilver halide in photographic emulsions, has been described and claimedin U.- S. Patent No. 2,110,491 of Salo. This patent points out thatphotosensitive emulsions, using acetyl cellulose esters particularlythose having anacyl content of -28%, are eminently suitable for use inthe photographic in dustry. The adherence however, of these emulsions ispogrwhen applied to a film base of an organic acid ester of celluloseand exhibits a tendency'to pull away at the edges during coating and toexhibit poor adherence to the film base during the processingoperations. Also, there is a tendency for these emulsions when supportedby film base of an organic acid ester of cellulose to form blisters whentreated in the conventional acid fixing baths.

These characteristics have interfered heretofore with the use ofcellulose ester emulsions for the preparation of photographic film.

One object of my invention is to provide a method of aifixing celluloseester emulsions to cellulose organic acidester film base,wherebypulling, sliding, blistering and dry stripping of the emulsionlayer from the film base, is elim-.

inated. Another object of my invention is to provide a gelatin-freephotographic film having good permanence in ordinary use. Other objectsof my invention will appear herein.

I have found that far-hydrolyzed cellulose organic acid ester emulsionlayers can be attached do cellulose esters employed for the photographicemulsions difler from those employed for the photographic film base inthe degree of hydrolysis, but also in many'instances the. composition-,oi acyl in the film baseester difiers from that of the ester employedas thecarrier for the silver halide. This invention is primarilyconcerned with the preparation. of photographic film in which the acylof the cellulose estersemplcyed essentially consists of fatty acidradicals of 2-4 carbon atoms. The far-hydrolyzed cellulose esteremployed as the carrier for the silver halide in the emulsion may be awater-susceptible cellulose acetate such as one having an acetyl contentbetween .20 and 28%, while the cellulose ester employed in the film basemay be a cellu-- lose acetate having a' relatively high acetyl content(such as-38-42 or a cellulose acetate propionate or a cellulose acetatebutyrate which may be substantially fully esterified or which maybehydrolyzed to some extent but not enough to appreciably diminish theWater resistance of the ester when formed intojsheeting. Instead ofusing. a straightacetate, the cellulose ester employed, as the carrierfor the silverhalide, may be a water-susceptible cellulose acetatepropionate which has been hydrolyzed down to an acyl content between 20and 28%. To coat this emulsion upon a water-resistant film base-would,to obtain good adherence,- necessitate intermediate subbing coatings.

,The accompanying drawing illustrates photographic film in accordancewith my invention.

to cellulose organic acid ester film base', if inter-' mediate subbinglayers are employed consistingof cellulose estershavingacyl contentsgradu-' ated between the cellulose ester of the emulsion layer and thatof the cellulose ester employed for the film base. Itis pointed out in,the Salo pat- .ent, referredto above, that the cellulose esters employedfor the photographic emulsion should be of a water-permeable nature inorder to assist;

the processing of the silver halide emulsion. Cellulose esters,-whichare employed for film base,

- on the other hand, should be resistant to Water so as to support aphotographic emulsion during the processing operation andalso to form asurface which is unaffected by water when the emulsion is coatedthereon; In order to obtain a film base having these characteristics, acellulose ester must be employed having properties dissimilar to thoseof the cellulose ester which is suitable for Figure I iilustratesaphotographic film composed of a film support in which the celluloseester is a cellulose acetate propionate having an acetyl content of 29%,a propionyl' content of 14.5%

,and an apparent acetyl content of 40%, 3 subbing layers of theindicated acyl contents and an emulsion layer as shown. Figure 2illustrates a photographic film in which only 2 subbing layers areemployed. a u f By employing cellulose esters for the subbing layers,having characteristicsas regards hydrolysis and as regards acylcomposition substantially intermediate between theester employed for theemulsion and that employed for the film base, good adherence of theemulsion to the film base is obtained and absence of stripping may beeffected. I have also found that the number of subbing layers may besubstantially decreased ,if a mixture of twoormore estersis employed foreach subbing layer. Where a mixture of esters is employed the difierencebetween the ap- Between film base and adjacent subbing Between parentacetyl contents of the' cellulose esters in each subbing layer should beno more than 9%. It is desirable to employ a sufiicient number ofsubbing layers that good adhesion is obtained between the film base andthe emulsion. I have found that there is seldom any casein ordinarypractice with cellulose ester emulsions and cellulose ester film basewhere more than three intermediate or subbing layers are required and,as a general rule, two subbing layers will b sufiicient, particularly ifmixtures of esters are employed in each subbing'layer, although the useof a greater number of subbing layers is within the scope of tent of thesubbing layer adjacent thereto should be no morethan 11%. Also, inaccordance with my invention, it isdesirable that the average apparentacetyl content of any subbing layer be no more than 3 /z% different fromthatof any ad'- jacent subbing layer. The average apparent acetylcontent ofthe subbing layer adjacent the emulsion layer should be nomore than 12 percent the am base ester and of the emulsion ester,

as described herein. These layers may be deposited from appropriatesolutions by any *meth od known to those skilled in the art, such as byimmersion, beading or the like, the support, being passed through or incontact with the solution at r such a rate that a layer of the desiredthickness will be laiddown on the material. In general, these subbinglayers are not morethan a few one hundred thousandths of an inch inthickness (such as .000025 in. thick) although thicker layers may beapplied in any case where excessive thickness is not objectionable.After each application of a subbing solution, the support is subjectedto an appropriate drying operation at atemperature sufiicient toevaporate the solvent.

Many different subbing layers of cellulose ester may thus be depositedupon the film support prior to applying the emulsion thereto.

The following examples illustrate my invention: r Example I A film basehaving a thickness of approximately'..005 in.,prepared by coating out asolution of a slightly hydrolyzed cellulose acetate propionate, havingan acetyl content of 29% and a propionyl content of 14.5% (apparentacetyl 40%) and a plasticizer, from propylene chloridedifferent than theapparentacetyl content of the cellulose ester of the emulsion. In thepreferred embodiment of my invention, it is desirable that the apparentacetyl contents differ as follows:

/ Per cent layer About6 Between adjacent subbing layers About 2 emulsionandadjacent subbing layer About '7 The cellulose ester emulsions towhich my invention is applicable are those described and claimed in theSalo Patent No. 2,110,491, referred to herein; The film base to which myinvention is applicable is any base prepared from a lower'fatty'acid'ester of cellulose in which theacyl consists of fatty acidradicals of 2-4 carbon atoms. For example, the film base prepared bycoating out a slightly-hydrolyzed cellulose acetate propionate and aplasticizerfrqm propylene chloride-alcohol, as described and claimed inMalm Patent ,No. 1,960,185, would be quite suitable for ,use herewith.The film base might be a cellulose propionate or cellulose butyrate oreven a cellulose triacetate. .In preparingthe film base, a solution ofthe cellulose ester is coated out onto a film-forming surface as atransparent layer, the

composition containing, inaddition to the cellulose ester, a.plasticizer such as triphenyl-phosphatein small amount and a volatilesolvent v therefor such as acetone, ethylene chloride or propylenechloride-methyl alcohol.. It is preferred that the conditions of coatingbe so contained. There is then deposited on this film base alcoholasdescribed and claimed in Malm Patent No. 1,960,185, dated May 22, 1934,was coated with an extremely thin coating consisting of a mixture of twocellulose acetate propionates A and B,

ester A which made up 40% of the mixture having an acetyl content of24.4%, apropionyl content of 13.9% and ester B which made up ofthemixture having an acetyl content of 22.5% and a propionyl content of12.8%. The layer was coated out on to the film base from a 2% solutionof the ester mixture in a solvent composed of acetone 28%, methanol 62%and cellosolve 10%.

After the first subbing layer on the film base had set anddried, asecond layer was applied thereover consisting of a ire of two celluloseacetate propionates A am. B, ester A which comprised'75% of the mixturehaving an acetyl content of 22.5% anda propionyl content of 12.8%, andester B which made up 25% of the mixture having an acetyl contentof.20.8% and a propionyl content of 12.6%. After this subbing layer hadset and dried, a third subbing layer trolledthat,"after evaporation ofthe solvent and the curing of the'film, a sheet or film of celluloseester, approximately .005-.010 in. thick. is, ob-

or film support a series of extremely thin layers of lower fatty acidesters of cellulose or preferably mixtures of these esters havingcharacteristics intermediate and graduated between those of.

was applied thereover. j This layer consisted of a mixture of twocellulose acetate propionates A" and B", ester A" which made up 25% ofthe. ,mixture having an acetyl content of 19.8% and a propionylcontentof 14.6%, and' ester B" which made up of, the mixture having anacetyl contentof 20.8% and a propionyl content of 12.6%. Both, thesecond and third layers were respectively. coated from 2% solutions ofthe mixture of .the cellulose. esters in a solvent having 'the samecomposition as employed in applyin the first subbing layer. This solventcomposition can be varied, however, as desired by the individualoperator or, if desired, other suitable solvent compositions may beemployed. I

After the last subbing layer had set and dried, a photographic emulsionlayer wasapplied thereto. ,The photographic emulsion was made, up ofsilver halide carried by, a far-hydrolyzed cellulose acetate propionatehaving an acetylco'ntent of 15.2%, a propionyl, content of 7.9% and anapparent acetyl content'of 21.5%, dissolved in a solvent mixtureconsisting fof'49%. ethyl alcohol,

49% water and 2% monoacetin. The emulsion -may, if desired, contain asensitizing dye or any other added materials to impart the desiredproperties thereto. Theemulslon layer was dried thus giving aphotographic film which is readilysusceptible to developing and fixingin the usual manner. i

Example II Toa filrn base the same as employed in Example I, a layer wasapplied consisting of approximately equal parts of two cellulose acetatepropionates, one having an acetyl content of 23.3%

- and a propionyl content of 16.5% and the other an acety'l content of19.8% and a propionyl conl tent of 12.8%. -.'ery dilute solution inorganic solvents such as This layer was applied from a employed for thesame purpose in the preceding example. After the subbing layer had setand dried, a second layer was applied thereto consisting of a mixture oftwo cellulose acetate p'ropionates, one which made-up 70% of the mixturehaving an acetyl content of l9.8%- and a propionyl contentof 14.6%, andthe second which.

made up the remainder of the mixture having an acetyl content of 20.7%and a propionyl content of 10.4%. After this subbing layer had dried, it

photo-sensitive emulsion layer was applied there-lto of the same natureand in the same manner as described in,thepreceding example.

Example IZ I To a film base, the same as employed in Example I, a'thinlayerwas applied consisting of 58%-0f a cellulose acetate propionatehaving an acetyl content of 23.3% and a'propionyl'content of.16.5% andof 42% of a cellulose acetate propionate having an acetyl content of19.3% and a propionyl content of 12.1%. This layer was coated out ontothe'film base from a.2% solution of the ester mixture in the samesolvents as employed for that purpose in Example I.- After the The termapparent acetylff as employed herein, refers to the acyl content-of thecellulose ester figured in terms of acetyl. For instance, if a celluloseester was a diester containing one butyryl group for every acetyl grouptherein,-the apparent acetyl would be the same as if both of the acylgroups were acetyl or, in other words, would be the same percentage asthe acetyl content of a cellulose di-acetate. The term .average apparentacetyl content refers to the average apparent acetyl content of acellulose ester composition. If the'composition consists substantiallyof all the same ester,. obviously the apparent acetyl content and theaverage apparent acetyl content is substantially the same. However, if.the composition consists of a mixture of esters, the average apparentacetyl. content will be the average of the apparent acetyl contents ofeach of the esters present, weight being given the apparent acetylcontent of each ester in accordance with the proportion of that esterwhich ispresents For instance, if a'composition consists of 75% of acellulose ester having an apparentacetyl con tent of 34 and 25% of acellulose ester having an apparent acetyl content of the averageapparent acetyl content of the composition will be approximately 33%.

Anyone familiar with cellulose esters would be able to supplyphotographic film of the type reefrredto in accordance with myinvention. How ever, analternative method, which might be employed forpreparing a photographic film in ac- 'cordance withmy-invention, wouldbe to depend subbing layer had set and was. dried, a photographicemulsion layer was applied thereto, which layer was made up of silverhalide carried by a far-l'iydrolyzed cellulose acetate 'propi'onatehaving an acetyl content of 15.2%, a propionylcontent of 7.9% and anapparent acetyl content of 21.5%, coated out from a' solvent mixturecontaim'ng ethyl alcohol and water in equal amounts. The emulsion layerwas dried and there'resulted a photographic V -Example IV A. film baseprepared by coating cut a solution of a slightly hydrolyzed celluloseacetate butyrate,

having an acetyl content of 30% and a butyryl content of 17 was coatedwith an extremely thin coating consisting-of a mixture of equal parts oftwo cellulose acetate butyrates, A and B,

ester A having an acetyl content of 28.9% and a butyryl content of 13%and ester B'having an acetyl content of 27% and a butyryl content of 7%.This layer wasappliedfrcm dilute solution in a mixture of organicsolvents. After this subbing layer had dried, it was coated with asecond layer consisting of a. mixture of .equal parts of two celluloseacetate butyrates, A' and B, ester A having an acetyl content of 28.3%and'a butyryl content of 11% and ester B having an acetyl content of 26%and a butyryl content of 5%. After this subbing layer had dried, aphotosensitive emulsion layer, in which the emulsion vehicle was acellulose acetate of 25% acetyl content, was applied thereto asdescribed in Example I.

. a propionyl content of 4 upon triangular graphs, such as shown in theprior art, for instance, in Malm Patent No. 2,078,- 261, dated April 27,1937. For instance, suppose the preparation of a photographic film wasdesired in which the cellulose ester in the emulsion 'to beused was acellulose acetate having an terms of apparent. acetyl and the distancebetween the emulsion layer point and the first point on'the line afterthat should be no more than 12% figured in ter'msirif apparent acetyl.The intermediate points should be much closer together so-that they areno more than 3%%- different figured as apparent acetyl.

It is preferable for the subbing layers that a mixture of cel-- luloseesters be used, selected by taking alternative points for the esterswhich are to'be mixed.

In that case the points adjacent the emulsion ester. and film base esterpoints would 'obviously' be selected less than 12% and 11% respectivelyfrom the latter points so that the average apparent'acetyl contents ofthe layers are within the terms of .my invention. ,It has been myexperience that by using a mixture of esters better results areobtained. With a line between the 'points, designating the emulsionester and thefilm baseester, anyone, even though unfamiliar withcellulose esters, can easily select a series of esters for subbinglayers in accordance with the instructions in this description whichwill cause good adherence between the film base and the organic acidester and thereb'etween at least one cellulose-organic acid estersubbing layer the acyl contents of which are graduated between thecellulose ester of the emulsion layer and that of the film base, thedifierence between the apparent acetyl content of the cellulose ester ofthe film base and the average apparent acetyl content of the subbinglayer adjacent thereto being no more than 11%, the difierence betweenthe average apparent acetyl contents of any subbing layers adjacent toeach other being no more than 3%;%,

the difference between the apparent acetyl content of the celluloseester in the emulsion and the average apparent acetyl content of thesubbing layer adjacent thereto being no more than 12% and the differencebetween the apparent acetyl difierence between the apparentacetyfcontents of substantially all of the cellulose esters ineachsubbing .layer' being no more than 9%.

high water resistance, an emulsion layer containr t. A photographiccomprising a film base layer comprising a cellulose-organic 'acid esterof such relatively high' acyl content that it has ing as the protectivecolloid a far-hydrolyzed cellulose-organic acid ester and therebetween aplurality of subbing layers made up of mixtures of celluloseesters, theaverage acyl contents of the subbing layers being graduated between thecellulose esters of the emulsionlayers and that of the filmbase, thediflference Between the apparent being no more than.3 /2%, thediflerence between the'apparent acetyl content of the cellulose ester inthe emulsion and the average apparent acetyl content of the subbinglayer adjacent thereto i being no morethan 12% and the difference be- 5.A photographic .film comprising contents of substantially all of thecellulose; es-

ters in each subbing layer being no more than 2; A photographic filmcomprising a-film base layer comprising a cellulose-organic acid esterof suchrelatively 'high acyl content that it has high water resistance,an emulsion layer containing as the protective colloid a far-hydrolyzedcellulose-'- organic acid ester and therebetween afplurality ofcellulose-organicacid estersubbing layers, the

tween the apparent acetylcontents of substantially all of the celluloseestersin each subbing layer being-no more than 9%., v q i .a film baselayer -,..comprising a cellulose-organic acid ester of such relativelyhigh'acyl content that it has high water resistance, an emulsion layercontaining as the protective colloid a far-hydrolyzed cellulose-organicacid ester and therebetween at least.one'cellulose-organic acid estersubbing layer the acyl-rbntents of which are graduatedbetweenthecelluldse ester of .the emulsion layer andxthat of-theifilmbase, the difference between acyl contents of which are graduatedbetween thecellulose ester of the emulsion layer and that of the filmbase, the difference between the apparent acetyl content of thecellulose ester'oi the film of the filmbase and the average apparentacetyl being approximately-6%, the difierence between the averageapparent acetyl contents oi'thesubbase and theaverage apparent aeetylcontent of the subbing layer adjacent thereto being no more than 11%,the difference. between the average bing layers adjacent to each otherbeing approxinmately 2% and the difierence between the apapparent acetylcontents of any} 'subbing .layers.

adjacent to each other being no more than 3 2%,

' the difference between the apparentacetyl content of thecellulose'ester in the emulsion and the average apparent acetyl contentoi the subbin -layer adjacentthereto being no more than 12% and thedifference between the apparent acetyl contents of substantially all ofthe cellulose esters in each subbing layer being no more. than;9

3. A photographic film comprising afilm base layer comprising acellulose-organic acid ester parent-acetylcontent of--the.celluloseester in the emulsionwand the average apparent acetyl contentof the subbing. layer adjacent'thereto being approximately 7% .and thedifference betially all-the cellulose ester-sin each: subbing layerbeing approximately 7%.;

of such relatively high acyl- -co n tent thatfit has high waterresistance; emulsion layercon- 6. A photographic filmcomprising afilmfbase layer comprising acellulose-organic acid ester of suchrelatively high acyl content that it has ".high water resistance, anemulsion: layercontaining as the protective colloid' aifar liydrolyzedcellulose-organic acid ester and'therebetween a phi- I rality ofcellulose-organio-acid' ester subbing laytaining as the protectivecolloid a far-hydrolyzed I cellulose-organic acid ester and therebetweensubbing layers made up of amixtureof. cellulose 3' that 0f the -b theence between esters, the acyl contents of thdsubbing ayers beinggraduated between the cellulose ester of theemulsion' layer and that ofthe film base, the diilerence between the apparent acetylcontent oflulose ester in the emulsion and-the average apparent acetyl content ofthe subbing layer-adjacent thereto being no more than 12% andthe thecellulose ester of the filmbase and'the averers,'the acylcontents-otwhich are-graduated between the cellulose ester-oftheemulsion layer theapparent-acetyl content of-theicellulose ester of the filrnbase. andtheaverage. apparent acetyl content-of the, subbinglayenadjacent thereto"parent acetyl 'content oi the cellulose ester in the emulsion and theaverage apparent acetyl content of the subbing layer adjacent theretobe- 7 ing approximately 7% and thedifference between the apparent acetylcontents '0': substantially all the cellulose esters in each sfibbinglayer being pprox mate y, v

aasasss age apparent acetyl content of the subbing layer adjacentthereto being approximately 6%, the difference between the averageapparent acetyl contents of the subbing layers adjacent to each otherbeing approximately 2% and the difference between the apparent acetylcontent of, the cellulose ester in the emulsion and the average apparentacetyl content of the subbing layeradjacent thereto being approximately7% and the" difierence between the apparent acetyl contents ofsubstantiallyall the cellulose esters in each I subbing layer beingapproximately 7%. Y

8. A photographic film comprising a, film base layer comprising acellulose-organicvacid ester 'of such relatively high acyl content thatit has high water resistance, an emulsion layer containing as theprotective colloid a far-hydrolyzed cellulose-organic acid ester andtherebetween a plurality of subbing layers made up of mixtures ofcellulose esters, the average acyl contents of the subbing layers beinggraduated between the cellulose esters of the emulsion layers and thatof the film base, the difierence between the apparent acetyl content ofthe cellulose ester of the film base and the average apparent acetylcon-' tent of the subbing layer adjacent thereto being approxima 1y 6%,the difierence between the average apparent acetyl contents of thesubbing layers adjacent to each other being approximately 2% and thedifference between the apparent acetyl content of the cellulose ester inthe emulsion and the average apparent acetyl content of the subbinglayer adjacent thereto being approximately 7% and the difierence betweenthe apparent acetyl contents of substantially all'the cellulose estersin 'each subbing layer being approximately'7%.

9. A photographic film comprising a cellulose acetate film base layerhaving a relatively high acetyl: content, an emulsion layer containingas the protective colloid a far hydrolized cellulose acetate andtherebetween at least one cellulose acetate subbing layer, the acetylcontents of which are graduated between the cellulose acetate of theemulsion layer and that of the film base, the difference between theacetyl content of the cellulose acetate of the film base and the acetylcontent of the subbing layer adjacent thereto be-- mg no more than 11%,the difference between the acetyl contents of any subbing layersadjacent to each other being no more than 3 the difference between theacetyl content of the cellulose acetate in the emulsion and the acetylcontent of the subbing layer adjacent thereto being no more than 12% andthe difference between the acetyl contents of substantially all of thecellulose acetates of each subbing layer being no more than 9%.

10. A photographic film comprising a cellulose acetate propionate filmbase of such relatively high acyl content that it has high waterresistance, an emulsion layer containing as the protective colloid a farhydrolyzed cellulose acetate propionate and therebetween at least onecellulose acetate propionate subbing layer, theacyl contents of whichare graduated between the-cellulose ester of the emulsion layer and thatof the film base, the difference between the apparent acetyl content ofthe cellulose ester of the filmvbase and the average apparent acetylcontent of the subbing layer adjacent thereto being no more than 11%,the difference between the average apparent acetyl contents of anysubbing layers adjacent to each other being nom'ore than 3 /2%, thedifference between the appar ent acetyl content of the cellulose esterin the emulsion and the average'apparent acetyl con:-

tent of the subbing layer adjacent thereto being no more than 12% andthe diflerence between the apparentacetyl contents of substantially allof the cellulose esters in each subbing layer being no more than 9%. v

11'. A photographic film comprising a cellulose .acetate -butyrate filmbase layer of such relatively high acyl content that it has high waterresistance, an emulsion layer containing as the protective colloid a farhydrolyzed mixed organic acid ester of cellulose and therebetween atleast one cellulose mixed organic acid ester subbing layer, the acylcontents of which are graduated between the cellulose ester of theemulsion layer and that of the film base, the difierence between theapparent acetyl content of the cellulose ester of the film base and theaverage apparent acetyl content of the subbing layer adjacent thereto,

tween the apparent acetyl contents of substantially all of the celluloseesters in each subbing layer being no, more than 9%;

WINFIELD PAB'I'RIDGE, JR.-

